High accuracy timepiece



Feb. 3, 1970 R. s. WALTON 3,492,896

HIGH ACCURACY TIMEPIECE Filed April 22, 1968 HIGH ACCURACY DIVIDER SECONDS TIMEBASE NETWORK TRANSDUCER INDICATOR MINUTE a FIG I INDICATOR IN VEN TOR. RICHARD S. WALTON ATTORNEYS United States Patent Ofifice 3,492,806 Patented Feb. 3, 1970 3,492,806 HIGH ACCURACY TIMEPIECE Richard S. Walton, Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Filed Apr. 22, 1968, Ser. No. 723,137

Int. Cl. G04c 3/04 US. CI. 58-23 Claims ABSTRACT OF THE DISCLOSURE The timepiece includes a high accuracy timebase coupled through a divider network to provide an output frequency of one pulse per minute. An electrical-mechanical transducer comprising a solenoid responds to the output of the divider network to directly step a gear connected to a minute indicator. The hour indicator is geared to the minute indicator. Actuation of the solenoid displaces a member against the bias of a spring. The spring biased member drives a gear coupled to an escapement to drive a seconds indicator during the one-minute interval between successive actuations of the solenoid.

BACKGROUND AND SUMMARY OF THE PRESENT INVENTION The present invention relates to a timepiece, and particularly to a high accuracy timepiece having low energy requirements. Specifically, the present high accuracy timepiece provides a high accuracy timebase coupled through an electrical-mechanical transducer directly to a minute indicator with a seconds indicator being driven through an escapement by energy stored by actuation of the transducer and released during the one-minute interval between the successive actuations of the transducer.

Conventional timepieces normally have a mechanical oscillator, such as a tuning fork or the like, which serves both as a regulator and a drive for the gear train. These oscillators are usually coupled to the seconds indicator with the minute and hour indicators being driven through a gear train connected to the seconds indicator. In such timepieces, the timekeeping base must set in motion .and overcome the rest inertia of the entire mechanical drive system at least once every second and in most such timekeeping mechanisms the drive train is mechanically pulsed many times per second whereby the rest inertia of the system must be overcome a like number of times per second. Considerable power is required to overcome this inertia and, in some instances, there are deleterious loading effects on the driving oscillator from the driven gear train.

According to the present invention, there is provided a timepiece having high accuracy minute and hour indications and reduced power requirements in comparison with the power requirements of conventional timepieces. The present timepieces, moreover, can operate over extended periods of time with very little accumulated error in the minute and hour indications. To provide these operating characteristics, a high accuracy timebase, which may comprise a high frequency oscillator, is provided, the output of which is divided by a divider network until the output frequency is one pulse per minute. A transducer comprising a solenoid converts this electrical pulse into a one pulse per minute mechanical movement of an armature which steps a gear directly connected to the minute indicator. An hour indicator is geared to the minute indicator in the usual fashion. In this manner, the rest inertia of the minute and hour train is overcome but once every minute and considerably less energy is required to step the gear train once every-minute as compared with conventional timepieces which step the gear train one or more times per second. Additionally, the usual loss of accuracy in minute indication through an excessive gear train is substantially eliminated. Moreover, the loading effect of the driven minute and hour indications on the driving oscillator is minimized.

It is another feature hereof that a seconds indicator is provided which is driven from the timebase but which does not impose energy requirements on the energy source during the one-minute interval between successive actuations of the transducer. To this end, the armature of the solenoid is coupled to an element which is displaced, in response to actuation of the solenoid, from a first to a second position against the bias of a spring. In thesecond position, the element is disposed in driving relation to a ratchet wheel, which, in turn, drives a seconds indicator through an escapement. The energy stored in the biased spring by the displacement of the element is sufiicient to drive the seconds indicator with an accuracy within tolerable limits for a full minute until the next actuation of the transducer. Thus, the rest inertia of the seconds indicator and its associated gearing is overcome by the energy stored in the spring and thus does not impose additional energy requirements on the energy source during the oneminute interval between successive actuations of the transducer.

Accordingly, it is a primary object of the present invention to provide a timepiece having low energy requirernents.

It is another object of the present invention to provide a timepiece having high accuracy in minute and hour indications.

It is still another object of the present invention to provide a timepiece having a high accuracy timebase coupled directly through an electrical-mechanical transducer to a minute indicator.

It is a further object of the present invention to provide a high accuracy timepiece wherein the rest inertia of the gear train of the minute and hour indication is overcome but once every minute.

It is still a further object of the present invention to provide a high accuracy timepiece having a seconds indicator requiring no additional energy from the energy source during the one-minute interval between successive actuations of the transducer.

It is a further related object of the present invention to provide a high accuracy timepiece having a transducer which is pulsed once every minute and which is coupled to the seconds indicator in a manner to store energy which drives the seconds indicator during the interval between successive actuations of the transducer.

These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, claims and appended drawings.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a block diagram schematically illustrating the power train of a timepiece constructed in accordance with the present invention; and

FIGURE 2 is a schematic illustration of a timepiece constructed in accordance with the principles of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings and particularly to FIGURE 1, there is schematically illustrated a power train for the timepiece hereof comprising a high accuracy timebase 10, the output frequency of which is divided by a divider network 12 to provide a frequency of one pulse per minute. The timebase 10 may comprise any suitable periodic signal source or oscillator, for example, a crystal controlled oscillator, a free-running or astable multivibrator, or any other type of signal source suitable for time-keeping purposes.

The structure and arrangement of timebase and divider network 12 are conventional and well known in the art and further description thereof is believed unnecessary. For present purposes, it is believed sufiicient to state that the divider network reduces the output frequency of timebase 10 to one pulse per minute.

An electrical-mechanical transducer 14 converts the one pulse per minute electrical signal from the divider network to a one pulse per minute mechanical movement which directly steps the minute indicator of minute and hour indicators generally indicated at 16, and provides energy to drive a seconds indicator 18 in a manner as will presently become clear. Specifically, and referring to FIGURE 2, electrical-mechanical transducer 14 comprises a solenoid 20 which is actuated once every minute in response to the output signal received from the divider network 12. An armature 22 is pivotally mounted to a support 24 and a spring 26 normally biases armature 22 into the illustrated position away from solenoid 20. It will be apparent that application of the divider network output pulse to solenoid 20 pivots armature 22 toward solenoid 20 against the bias of spring 26 and removal of the pulse from solenoid 20 permits armature 22 to return under the bias of spring 26 to the illustrated position.

Minute and hour indicators 16 comprise a ratchet wheel 28 mounted on a shaft 30 which carries a minute hand 32. Shaft 30 is connected through suitable gears 34 to a shaft 36 which mounts an hour hand 38. In this form, shaft 36 is concentric about shaft 30. The free end of armature 22 is disposed in driving relation to ratchet wheel 28 whereby actuation of solenoid 20 once every minute causes armature 22 to successively step wheel 28. Minute hand 32 is accordingly directly stepped with ratchet wheel 28 with hour hand 38 being advanced via gear train 34 and shaft 36. The rest inertia of the minute and hour indicators is thus overcome once every minute and, with the minute indicator being directly stepped by the transducer, the minute indicator obtains an accuracy substantially identical to the accuracy of timebase 10.

The seconds indicator 18 comprises a shaft 40 mounting a second hand 42 at one end, shaft 40, in this form, being disposed concentrically within shafts 30 and 36. Shaft 40 is coupled to a ratchet wheel 44 via suitable gears 46 and a shaft 48. An arm 50 depends from armature 22 and is engageable against a movable member 52. In this form, member 52 is mounted for translatory movement in a support 54 and is supported by a spring 56. It will be seen that actuation of solenoid 20 causes arm 50 to displace element 52, downwardly as seen in FIGURE 2, against the bias of spring 56 whereby the tip 58 of element 52 is disposed in driving relation to ratchet wheel 44 urging its rotation in a clockwise direction. Rotation of second hand 42 via shaft 48, gears 46 and shaft 40 under the bias of spring 56 is restrained by an escapement indicated at 60 including an index wheel 62 mounted on shaft 40. Escapement 60 may comprise a conventional balance wheel and hairspring assembly 64 and pallet 66. It will thus be seen that the torque applied to index wheel 62 by spring 56 via wheel 44, shaft 48, gears 46 and shaft 40 cooperates with the hairspring and balance wheel assembly 64 to oscillate pallet 66 whereby index wheel 62 is stepped unidirectionally to advance second hand 42 through shaft 40. Thus, spring 56 acts as an energy source for seconds indicator 18 during the oneminute interval between successive actuations of solenoid 20 whereby the rest inertia of the gear train of the seconds indicator is overcome by spring 56 rather than by transducer 14.

The accuracy of the timepiece constructed in accord ance with the principles hereof can provide minute and hour indications having an accuracy of 1:.001%. A low accuracy (:1%) and hence less costly escapement can be provided herein and this would provide sufficient accuracy without correction for the seconds indication for most practical applications. If greater accuracy in the seconds indication hereof is required, an overall accuracy of one second can be obtained by periodically correcting the position of the second hand. It will of course be appreciated that the second, minute, and hour hands 42, 32, and 38, respectively, may be replaced by counter wheels or rotating discs.

It will thus be seen that the objects of the invention are fully accomplished in that there is provided a timepiece having high accuracy and low energy consuming minute and hour indications. Specifically, it will be noted that the rest inertia of the minute and hour indications is overcome once every minute in contradistinction to conventional timepieces wherein the rest inertia of the entire gear train must be overcome once or more each second through the seconds indicator, whereby the present timepiece requires substantially less power than conventional timepieces. Moreover, it will be seen that the rest inertia of the seconds indication gear train does not represent an additional power drain on the energy source during the interval between successive actuations of the transducer and is not overcome by the power source but rather is independently overcome by the energy storing spring.

What is claimed and desired to be secured by US. Letters Patent is:

1. A timekeeping mechanism comprising a high accuracy timebase including an oscillator and providing an electrical signal, an electrical-mechanical transducer connected to said timebase and having a member movable periodically in response to said electrical signal, a minute indicator, said member being disposed in direct driving relation to said minute indicator to advance the latter in response to movement of said member, a seconds indicator, means connected to said transducer for advancing said seconds indicator, said connecting means including a gear coupled to said seconds indicator, a movable element, means coupling said member to said element to move said element from a first position to a second position in response to movement of said member, said element being disposed in driving relation to said gear when in said second position, a spring biasing said element from said second position to said first position, and an escapement coupled to said gear whereby said element drives said seconds indicator through said gear and escapement.

2. A timekeeping mechanism comprising a source of periodic signals, a movable member, means responsive to said signal source to move said member once every minute, a minute indicator, said movable member being disposed in direct driving relation to said minute indicator to advance the latter in response to movement of said member, a seconds indicator, and means connected to said movable member for storing energy in response to movement of said member and means for releasing the stored energy between successive mechanical movements of said member to advance said seconds indicator.

3. A timekeeping mechanism comprising an electromechanical energy transducer including a movable member, a source of periodic excitation signals for said transducer, said transducer being responsive to said signal source to move said member about once every minute, a minute indicator, means coupling said movable member to said minute indicator to advance the latter in response to movement of said member, a seconds indicator, means connected to said movable member for storing energy in response to movement of said member and means for releasing the stored energy between successive mechanical movements of said member to advance said seconds indicator.

4. A timekeeping mechanism according to claim 3 wherein said releasing means includes an escapement.

5. A timekeeping mechanism comprising an electromechanical energy transducer including a movable member, a source of periodic signals for said transducer, said transducer being responsive to said signal source to move said member once for every successive predetermined time interval, a first time indicator, means coupling said movable member to said first indicator to advance the latter in response to movement of said member, another indicator for indicating successive time intervals substantially shorter than said predetermined time interval and within said latter interval, means connected to said movable member for storing energy in response to movement of said member and means for releasing the stored energy between successive mechanical movements of said member to advance said other indicator.

6. A timekeeping mechanism according to claim 5 wherein said predetermined time interval is about one minute.

7. A timekeeping mechanism according to claim 5 wherein said shorter time interval is about one second.

8. A timekeeping mechanism according to claim 5 wherein said predetermined and shorter time intervals are about one minute and one second respectively, said first and other time indicators comprising minute and second indicators, said transducer including a solenoid, said signal source including a divider network providing an output signal to said solenoid of about one pulse per minute, said solenoid being responsive to said output signal to advance said minute indicator.

9. A timekeeping mechanism according to claim 2 wherein said release means includes an escapement.

10. A timekeeping mechanism according to claim 1 wherein said transducer includes a solenoid and an arm movable in response to actuation of said solenoid, said arm being coupled to said element to move said element from said first position to said second position against the bias of said spring.

References Cited UNITED STATES PATENTS 1/1965 Reich 5823 2/1965 Baehni 58-23 US. Cl. X.R. 5-8-40 

